In all honesty, I wouldn't recommend SLI at all.
I'd get one 8800 Ultra, and spend the additonal money elsewhere.
If you're building this week, then Intel definately performs noticibly better... though many AMD fanboys have been following the upcomming Phenoms, which might be good. I don't know about that though... I haven't been watching AMD's stuff too close.
With what is out today, Intel is on top by quite a bit.
I'd recommend building it yourself, through (mostly) Newegg
. However, I did notice that Buyxg site does indeed have Intel CPU's and Motherboards. Got there from the main page... just look around a bit.